(RxWiki News) How many times have you heard, “Eat more fruits and vegetables”? Maybe your mother was the first one to give you this advice. But do fruits and vegetables make a difference in your cancer risk? Depends on who you ask.
A recent study found that women who ate diets high in fruits and vegetables had fewer cases of invasive (spread beyond the organ) bladder cancer than women who didn’t eat as many fruits and vegetables.
An expert in bladder cancer, Ralph W. de Vere White, MD, director of the University of California, Davis Comprehensive Cancer Center, disagrees with this study’s conclusions.
"Eat more fresh fruits and vegetables."
Song-Yi Park, PhD, a cancer researcher at the University of Hawaii Cancer Center, Honolulu, directed this study to see if and how dietary patterns impacted bladder cancer risks.
The prospective study examined whether consuming fruits and vegetables or other nutrients found in them affected the bladder cancer risks of 185,885 older adults participating in the Multiethnic Cohort Study.
The cohort (group) was formed between 1993 and 1996. The participants — men and women between the ages of 45 and 75 — completed a 26-page questionnaire about their eating habits over the previous year.
The researchers followed the Surveillance, Epidemiology and End Results (SEER) registries of California and Hawaii through 2007 to determine the number of bladder cancer cases diagnosed among the group.
A total of 581 invasive bladder cancer cases (429 men and 152 women) were diagnosed among the study participants.
The researchers found that women who consumed the most fruits and vegetables overall, the most total vegetables, yellow-orange vegetables, total fruits and citrus fruits had lower risks of invasive bladder cancer.
Women with the highest intake of vitamins and minerals found in fruits and vegetables, including vitamins A, C, E and beta-carotenes, also had lower risks of bladder cancer.
Fruit and vegetable and nutrient intake didn’t impact overall bladder cancer risks in men. However, in subgroups of men, the study found that vegetable consumption reduced the bladder cancer risks of male smokers, and fruit and vegetable intake was associated with lower cancer risks in Latino men.
UC Davis’s Dr. de Vere White didn’t believe any of it. “Eating a healthy diet, staying fit and not smoking are clearly good for your health. But the findings detailed in this paper do not prove that a diet high in vegetables and fruits will reduce someone's risk of developing non-muscle invasive bladder cancer. This form of cancer accounts for 75 percent of cases,” Dr. de Vere White said.
Non-muscle invasive bladder cancer spreads into the connective tissue of the bladder, but not into nearby muscles.
“The authors show that there is a reduced risk of muscle-invasive bladder cancer that is associated with a high intake of fruits and vegetables, but only in women,” Dr. de Vere White continued.
“It is somewhat counterintuitive that a diet would fail to prevent the development of the least aggressive type of cancer (non-muscle invasive), but would be able to prevent the most aggressive type, muscle invasive. Nor do the authors provide any scientific evidence to show a possible molecular mechanism to explain their findings,” said Dr. de Vere White, who is associate dean for cancer programs and distinguished professor of urology at UC Davis.
Bladder cancer will be diagnosed in an estimated 72,570 adults (54,610 men and 17,960 women) this year, according to the American Cancer Society.
This study was published in the August issue of the Journal of Nutrition.
The study was supported by the National Institutes of Health. No conflicts of interest were declared.